1. Field of the Invention
This invention generally relates to sealing arrangements for pipe joints and more specifically to an improved clamping device for effecting a seal between a pipe and a manhole.
2. Description of Related Art
Various proposals exist for connecting pipes to manholes in sewer systems. For example, U.S. Pat. No. 3,958,313 for a Method, Apparatus and Product for Improved Pipe-to-Manhole Sealing issued May 25, 1976 to the same assignee as the present invention discloses an underground joint between a sewer pipe and a reinforced concrete manhole riser. A flexible boot slips over the free end of the pipe and an external clamp compresses the seal onto the pipe to produce a boot-to-pipe seal. The other end of the boot penetrates an aperture in a manhole through a normally core-drilled opening in a riser wall. The end of the boot fits in the aperture. A clamping assembly with a clamping band and an integral toggle expander fits inside the boot in alignment with the riser wall. When the toggle expander is operated, it expands the band into the boot and compresses the boot against the riser to produce a boot-to-riser seal.
Occasionally it is necessary to remove the connector from the riser because of improper installation of the seal or an incorrectly sized clamping assembly. In these cases both the clamping band and toggle, which constitute an integral unit, must be replaced.
Core drilling through a concrete riser wall produces a porthole of nominal diameter, but occasionally because of core drill out-of-roundness caused by damage, the actual size will vary. Optimum sealing then requires an accomodation which was difficult to realize with an integral toggle and clamp. The clamping band and toggle also include three hinge joints. These joints require special machining operations that add to the manufacturing costs.